1. Field of the Invention
The invention is related to the field of Local Number Portability (LNP) capability, and in particular, to a method for testing a LNP-ported telephone number.
2. Statement of the Problem
Local Number Portability (LNP) is a scheme for allowing persons (and/or institutions) to keep an existing telephone number. The LNP capability allows a subscriber to keep an existing telephone number even when the subscriber physically moves or when the subscriber changes telephone service providers. The LNP capability enables subscribers to move or change service providers without the need to inform all potential callers of a new telephone number. The LNP process is transparent to both the caller and the called party.
Before LNP, telephone numbers were assigned to a local service-provider's end offices on an NPA-NXX basis. An NPA-NXX is defined as the Numbering Plan Area (NPA) and an office code (NXX) of an end user's telephone number (e.g., 123-456-7890). Each NPA-NXX can include up to 10,000 different telephone numbers. In the past, a telephone number identified the person/telephone, as well as the actual end office or telephone switching system that served the person. As a result, the dialed NPA-NXX was the terminating switch's routing address to the rest of the network. With the implementation of LNP, which allows any number of local service providers to serve the same NPA-NXX, this routing scheme could no longer be used.
The LNP architecture utilizes a unique 6-digit LRN to identify each switch in the network for call routing purposes. Each switch is assigned a LRN. Consequently, a LNP information entry correlates a dialed (i.e., destination) telephone number to a LRN of a terminating switch. The LRN is used to route the call to the terminating switch, and the original dialed telephone number is then used by the terminating switch to complete the call.
FIG. 1 shows a conventional prior art LNP process, wherein a destination telephone number has been ported using the LNP capability. The source telephone initiates a telephone call to the destination telephone by dialing a destination telephone number. The dialed number is received in a local (originating) switch. The originating switch can signal a routing resource, such as a Signal Control Point (SCP), in order to obtain routing information for the destination telephone. The originating switch performs a “LNP dip” and accesses a LNP database or other LNP information. If the dialed number is in the LNP database, the telephone number has been ported via local number portability. If the dialed number is not in the LNP database, the dialed number is used to route and connect the telephone call. In this example, the LNP dip produces a 10 digit number, where a Location Routing Number (LRN) is the first 6 digits. Herein the term subLRN refers to the use of all 10 digits for routing and connecting the telephone call, rather than using just the 6 digit LRN. This 10 digit number is substituted into a Called party Number Field (CdPN) of the call signaling, replacing the dialed number. The dialed number, however, is retained in a Generic Address Parameter (GAP) field of the call signaling for future use. The SCP provides the LRN and the dialed number back to the originating switch. The originating switch then routes and connects the telephone call to the terminating switch. The telephone call can transit any number of intermediate switches. The terminating switch receives the telephone call, according to the LRN (i.e., the first 6 digits of the called party number parameter). The terminating switch recognizes its LRN, retrieves the original dialed number from the GAP, and connects the telephone call to the destination telephone using the dialed number.
When a LNP dip is not performed for a ported number (e.g., the originating switch is not LNP capable) or when the LNP dip fails, then the call will be routed based on the originally dialed telephone number. The call will accordingly be routed to the switch from which the number was ported. This switch will perform a LNP dip and will route the call based on the LRN obtained from this LNP dip.
On occasion, a new switch is added to a telephone network. A new switch may be added for various reasons, including replacement of an existing switch, upgrading of an existing switch, adding a switch to handle increased number of subscribers, adding a new switch as an interface to another network, etc. The addition of a new switch will likely require assignment of a LRN number to the new switch. In addition, the routing information of existing switches will need to be updated in order to properly route a call that includes the LRN of the new switch. If the routing information for the LRN is incorrect, calls to telephone numbers assigned to the new switch will fail.